I think this will work OK. Check how fast your builds on such agent and than decide.

Please note that builds under TeamCity work more slowly than under command line. This happens because build runtime information is sent to the TeamCity server while build is running. This allows to provide faster feedback from builds.

Interestingly your last post there - almost sounds like an invitation for a Feature Request.

Given that I would imagine that most builds run unattended with users only taking an interest once the result of the build is known (and presumably getting on with other things in the interim), there's perhaps room for a config option which send back less information to the build server to increase the throughput.

The other possibly related issue I notice (and this might just be related to the low spec of my evaluation machine) is that when TeamCity gets sources from TFS, this seems to be dramatically slower than doing a similar action in VisualStudio. I wonder if this is a similar problem?